In on-axis applications (e.g. central projection), such projection device is always disadvantageous insofar as at least part of each generated reflection ray bundle also passes through the second partial optics and is thus projected onto the projection surface. This causes the on-off contrast as well as the uniformity of the black image (wherein a planar black image is to be displayed) to deteriorate.
In order to prevent such reflection-related deterioration of the displayed image, the illumination light was previously directed onto the pixels by total internal reflection via a prism. However, such a prism is a relatively expensive component and requires an expensive anti-reflection coating. Further, the path in glass leads to undesirable chromatic aberrations.
In view thereof, it is an object of the invention to improve a projection device of the above-mentioned type such that the influence of illumination light reflections on the image quality of the projection is reduced.